Understanding the guest binding in the cucurbit[7]uril inclusion complexes of CDK4/6 inhibitors, palbociclib, and ribociclib from a combined experimental and computational study

•The binding of the anti-cancer drugs, palbociclib and ribociclib with cucurbit[7]uril in inclusion complexes was studied in solution and solid-state by NMR, MALDI-TOF, ITC, DSC, PXRD, and DFT computations.•The co-amorphous CB[7] inclusion complexes of anti-cancer drugs show enhanced thermal stability.•Three new crystalline forms of the palbociclib oxalate salt were identified, and the phase interrelationship between them was studied with the help of PXRD and DSC.•We also report the structural characterization of palbociclib oxalate monohydrate and the DMSO solvate of ribociclib succinate dihydrate by single-crystal X-ray diffraction.